No government can just magic private sector jobs out of nowhere. They could offer subsidies and tax cuts to some companies though, is that what would like Labour to do? Both this, and creating jobs in the public sector would be expensive. Or, do you mean public investment in projects /infrastructure to provide more jobs and economic growth?
But there are things they could do, like allow pension funds to directly invest in UK infrastructure. One of Gordon Browns wheezes was to further limit the risk holdings of UK pension funds underpinning Gilt sales he wanted to make but locking them out of direct investment in infrastructure. UK wind farms, utilities etc are often directly invested in by foreign pension funds but not UK ones. The additional capital that might flow into infrastructure if UK pension funds were able to invest would be a boost to the economy.
Reducing the cost of moving house would improve the economy by increasing job mobility. We all complain about the preponderance of the South East in our economy yet even if you move jobs out it's viciously expensive for people to move to take economic opportunities.
A national plan to reduce the cost of child care, for too many people the choice is work or child care because of the expense this has lifetime impacts on womens earnings and hits productivity as competent young women leave the job market.
There are things that can be done but Labour normally want to throw cash at the problem first, second and last. I think there is genuine room for Labour to differentiate themselves from the Conservatives without having to promise jam today, jam tomorrow, jam for everyone.
I'd vote for them once, if it meant I never had to vote for them again 
